FIGURE 4.

hCLEC9A is an endocytic receptor. A, internalization of CLEC9A expressed in NIH3T3 fibroblasts, following antibody cross-linking, was determined by flow cytometry. The analysis, performed by comparing cells incubated at 37 versus 4 °C (to prevent internalization), demonstrates that hCLEC9A is rapidly removed from the cell surface following cross-linking, indicative of receptor endocytosis. Dectin-1, previously shown to be endocytic (19) was included as a control. The data shown are mean ± S.D. of triplicates, and representative of three independent experiments. ^*, p < 0.05 versus control (Student's t test). B, fluorescent microscopy demonstrating internalization of CLEC9A (red) into LAMP1⁺(green) vesicles, as indicated following cross-linking and incubation at 37 °C versus 4 °C. Nuclei are stained with DAPI (blue).